D'awww, they don't get their own names? Aren't they special enough?Change the names of all item delivery NPCs to "Item Delivery." It's not like any of them are ever important to the game's story, so they really don't need to have unique names anyway. "Item Delivery" as a name would work fine.
Just kidding, but I do like the idea of having a mailbox outside of the home. We do it in real life for the very same reasons!